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Caresheet: Assassin snail | Clea helena

September 13, 2015
assassin snail

Even the most careful aquarist can end up with a snail infestation, which can be rather frustrating! In the search for a solution they often look up which fish eat snails and eventually end up with a puffer or clown loach, which is entirely unsuitable for their setup and an even bigger problem than before. Luckily, there is another option: assassin snails, so called because they skillfully hunt down and cannibalize other snails. Keep reading for more information on keeping assassin snails and their effectiveness when dealing with a snail infestation!

Tank size 10 gal (38L)?
Temperament Moderate
Diet Carnivore
Temperature 75-80°F/24-26.5°C
pH 7.5-8.0


Assassin snail, Clea helena (sometimes Anatome helena), bumblebee snail

Assassin snail natural habitat

Assassin snails are naturally found in Southeast Asia, where they reside in all types of streams and ponds with sand substrate.

Assassin snail appearance

Their conical, yellow and dark brown striped shell makes assassin snails an attractive addition to any aquarium, not just the ones with a pest snail infestation! They usually grow to a maximum size of around 0,5 inch/1,3 cm, although slightly bigger snails have been reported. Like many other snail species they use a siphon, which can usually be seen sticking out of the shell, to breathe. Telling males and females apart is not really possible.

Assassin snail requirements

Although they are not really group animals, keeping at least 3-4 assassin snails is usually recommended. There seems to be a bit confusion about the minimum tank size for them, but at least 10 gallons (38L) should definitely be enough for a group that size! Because assassin snails naturally bury themselves and wait for their prey to appear a sand substrate is preferred, although it’s not a must. The water should ideally not be too soft, as this could lead to deterioration of the shell, and as with all tropical fish and invertebrates the aquarium should be filtered, heated, fully cycled and free of ammonia and nitrites.

Assassin snail tankmates

If you’re thinking about introducing assassin snails into your aquarium, keep in mind that they don’t just eat pest snails. Although not all sources agree on whether they will also devour ornamental nerite snails and even large mystery snails, you should definitely assume they will and avoid keeping them together. In fact, assassin snails will eat about anything that comes their way: planaria, fish eggs, and according to some aquarists, even the occasional dwarf shrimp fry. This means that if you’re breeding your fish or shrimp and want to avoid any risks, you may want to skip the assassin snails. Any larger tankmates that require the same water values are fine, as long as they’re not snail eaters!

Assassin snail diet

As mentioned before, assassin snails are not strictly snail eaters. While they can wipe out entire populations of pond snails, ramshorn snails and Malaysian trumpet snails, they are opportunists that will eat anything that comes their way. This means live prey, deceased tankmates, commercial fish foods, frozen foods and even algae. To feed a steady supply of snails once the initial population is gone, you can ask your local aquarium store or breed snails in a small separate tank as described here. However, there is no need to worry if you do ever (temporarily) run out. Feeding your assassins other protein rich foods such as bloodworms is fine as well!

Assassin snail behavior

Although they will quickly flock to any food that is offered, assassin snail behavior is very different from that of most of their herbivorous cousins. They don’t move around foraging, but the hunting process is quite interesting to watch!

When they’re hunting for live snails, they will bury themselves into the substrate whenever possible and wait there with just their proboscis (feeding tube) sticking out until an unsuspecting victim gets close enough to assassinate. If there is no sand substrate available to bury in, they will often actively move around the aquarium while searching for other snails to devour.

Breeding assassin snails

Fortunately, while breeding assassin snails is not very difficult, it’s not as easy as breeding pest snails or you would soon end up with an assassin snail infestation. If you do end up with more assassins than you can house after a while, it’s usually not too difficult to find another aquarist or aquarium store willing to take a few.

Like mystery snails and unlike pest snails, assassin snails are not hermaphrodites where both sexes can reproduce. Instead, only the female can reproduce, which means a lot less offspring. To breed, get a big enough group to have a good chance of having both sexes in there, as the males and female’s can’t be told apart. As long as there are plenty of snails or other nutrient and protein rich foods available, the snails will take it from there! You should soon see light colored, square shaped egg sacs appear. After hiding for a while until they’re big enough, the baby snails will join the adults during feeding time.

Buying assassin snails

When buying, look for assassin snails that are actively moving around, eating or stalking prey in the substrate. If the operculum is closed, there may be something wrong with the snails. A flaky looking or deteriorating shell is a sign of calcium deficiency, which may be too late to reverse. If you’re ordering online, be sure to look for a trustworthy seller with plenty of good reviews like InvertObsession!

When introducing your snails into their new home, make sure you acclimate them properly so they can slowly adapt to the different water values. Skipping this step means a lot of stress for the snails, which can unfortunately sometimes be fatal!

Although assassin snails do a great job at keeping aquariums snail free, their striking stripes and interesting feeding behavior also make them a great addition to setups without a snail problem. They are fun to watch when hunting and do well in a wide range of water conditions!

If you have any more questions about keeping assassin snails or want to share your experiences with them, be sure to leave a comment below. Happy snail keeping!

Cover photo: Om Nom Nom by f_jean

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  • Reply Denny September 24, 2015 at 8:44 am

    Hello . Loved your post. please tell me, do you know if assassin snails can be fed with garden snails? Will it ruin the tank water?

    • Reply Mari September 24, 2015 at 8:57 am

      Hi! I don’t think feeding assassin snails with garden snails is a good idea, they contain all sorts of stuff the assassins won’t be used to! If you’re having trouble finding pest aqurium snails to feed them, try asking around at pet- and aquarium stores 🙂

    • Reply Ginger October 3, 2015 at 3:04 am

      hi um if you need snails please email me at vrdoran@gmail i have so many ramhorns they are extremely free

  • Reply Psybur September 14, 2015 at 1:37 am

    What the hell is that noise in the background of the video?

    • Reply Mari September 15, 2015 at 10:06 pm

      It’s not my video so I’m not sure actually, sorry! I tested it before posting and I didn’t notice anything too strange/excessively loud… it just sounds like a machine running in the background to me. Or are you hearing something completely different?!

      • Reply Psybur September 16, 2015 at 4:19 am

        Sorry, I didn’t mean to come off so brusque. I was just saying it regularly (I swear a lot, sorry). I just found it humorous that it was happening.

        • Reply Mari September 16, 2015 at 9:45 am

          No problem haha! After the incident where I didn’t notice the reflection of a naked guy’s chest in a video of a rosetail betta I was just worried maybe I missed a strange or inappropriate sound…

          • Psybur September 18, 2015 at 7:23 am

            ROFL, he’s probably in the background murmuring, ‘I’m too sexy for my shirt. . . ‘ while that’s going on! That’s hilarious; is that video still there?

          • Mari September 18, 2015 at 4:29 pm

            It’s not in the article any more, but I had a look on Youtube for you and managed to find it again here… I hadn’t even noticed it until a commenter pointed it out haha. 🙁

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